Synthesis, Characterization, and Morphological Control of Cs₂CuCl₄ Nanocrystals

Recently, there has been an increase in research relating to the search for new optoelectronic materials for photovoltaic devices and light-emitting diodes. This research focuses on developing materials that not only possess the required optoelectronic properties (high absorption, efficient photon emission, and high charge-carrier mobilities) but are also solution-processable, which can reduce fabrication costs. Ternary ionic crystal structures, such as lead-halide perovskites, have emerged as a class of such suitable materials. However, the most promising structures, which exhibit the highest device efficiencies, rely on toxic lead as a cationic species, thereby hindering commercial application. Here, we synthesize and characterize CsCuCl₃ and Cs₂CuCl₄ nanocrystals. These nanocrystals exhibit bright broad band green emission from copper defects when excited below 300 nm. We show that by employing a variety of ratios of coordinating solvents during synthesis, we can tailor the morphology of the nanoparticles produced, allowing us to produce structures such as dots, platelets, and rods. These materials represent a new class of nontoxic, solution-processable ternary semiconductors for optoelectronic applications.